Thermostatic compensating unit



Aug, 22, 1950 v w, J, RADY Er-AL 2,519,601

THERMOSTATIC COMPENSATING UNIT HVVE'NTOQS WILL/AN J QQY Patented Aug. 22, 1950 UNITED STATES PATENT OFFICE THERMOSTATIC COMPENSATING UNIT William J. Rady and Lyman A. Rice, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Claims. 1

This invention relates to carbon-pile regulators for controlling either the voltage or the current produced by a variable speed generator, and is a division of our copending application Serial No. 609,670, filed August 8, i945, now Patent No. 2,478,835, dated August 9, 1949.

An object of the invention is to provide means for compensating for the eiiect upon the regulator caused by expansion oi carbon-pile discs due to temperature increase.

A -further object is to provide means for stabilizing the operation of the regulator particularly when there is a sudden change in load upon the generator regulated thereby Further objects and advantages ci the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

Tn the drawings:

Fig l is a longitudinal, sectional view of a regulator embodying the present invention;

Fig. 2 is a sectional view of a thermal responsive unit which compensates for expansion and contraction of the carbon-pile due to changes in temperature.

Referring to Fig. 1, a suitable :mounting base, not shown, supports brackets I and which support a tubular frame l2 of magnetizable material having a partition 3 having a central opening i4 which receives the central magnetizable core |5 attached to a magnetizable plate I5 attached to the frame I2. Core I 5 supports a nonmagnetizable sleeve l'l which insulatingly supports magnet coils i8 and I9.

connected across the generator terminals and coil I9 is used as an equalizer coil when a plurality of voltage regulators are used for controlling generators which charge a common storage battery. In case of the current regulator, the coil I8 is responsive to battery charging current.

The frame I2 supports a plurality of studs 29, the right ends of which are attached to a radiator 2| having heat dissipating fins 22. Radiator 2| encloses an electrically insulating ceramic tube 23 of good thermal conductivity enclosing a plurality of carbon discs 24 which are in contact with electrodes 25 and 2S. Electrode 25 contacts a metal disc 2l attached to the end of a screw 28 f threaded through a boss 29 provided by a plate 3U, insulatingly supported by the radiator 2|. Boss 29 is cut part-Way by a saw cut 3| to provide a part 29a which can be caused to spring toward the part 29 by turning a screw, ,not shown,

Ii the regulator is used for regulating voltage, the coil I8 will be which passes through a plane hole in the part 29a and is screw-threaded into the part 29. A cap 32 attached to the plate 39 in any suitable manner protects the outer end of the screw 28. Electrode 26 is in contact with a metal disc 35 attached to the base of a strut 35 having a plurality of legs 3l of relatively small cross-sectional dimensions and providing a relatively great heat radiating surface. The strut legs 3'! are connected with a terminal plate 38 to which a terminal screw 39 attaches a Wire 69. The wire i9 and the plate 39 are connected into the circuit of the generator neld coil.

The partition i3 and the core i5 provide pole faces adjacent to an armature 4| which is maintained in central location by a plurality of spring fingers 42 extending radially from and integral with a plurality of discs 43 made of spring metal such as stainless steel. The discs i3 are separated by spacers 44. The left hand disc 43 is separated from armature 4l by a disc 45. The right hand disc 43 is separated by metal spacer 46 from a mica spacer 4l located between the discs 4S and terminal plate 33. The metal discs are secured to the armature 4| by screws 48 and 49, the latter serving also to secure the plate 38 and the mica disc 4l to the other discs and to the armature. As .shown screws 49 are insulated from the plate 38. The ends of the spring ngers are spaced slightly from the cylindrical wall l2a of frame I2 and bear against a ring 59 of non-magnetizable metal and having good thermal conductivity. Ring 59 is in good thermal contact with the wall |2a, so that heat extracted by the member 50 from the spring lingers 42 will be readily transmitted into the frame l2.

Between the member 59 and the partition |3 there is located a disc 5| of resilient non-mag-r netizable metal which is attached to the armature 4 I, a spacer ring 52 and a magnetizable metal disc 53. Between the discs 5| and 53 air is trapped for a purpose to be described later. The spring lingers 42, being normally biased toward the ring 5B, cause the armature 4| to be urged toward the right thereby causing pressure to be exerted through the strut legs upon the carbon discs 24. Obviously, the initial pressure uponI the discs can be regulated by turning the screw 28.

In order to exclude dust from the movable parts of the regulator, the frame l2 provides a recess defined by a ledge which receives a seal ring of glass covered music wire 55 against which bears the flange 5'! of a housing 58 having a central opening in its right wall denecl by the portion 59 which bears against a glass covered music wire ring 6U in a recess 6I provided by radiator 2 I. To the interior of the right wall of housing 58, there are attached a plurality of resilient arms 62 extending radially from a ring 63 having an annular flange 64 bearing against the left end of the refractory tube 23. As the temperature of the regulator increases, radiator 2| will expand faster than the tube 23 thereby deecting the portion 59 of the housing relative to the iiange 64 of ring 63 which remains in contact with the tube due to the bias of the resilient arms 62. Housing 58 supports a grommet 65 through which the wire 40 passes.

In copending application of William J. Rady, Serial No. 509,454, filed November 8, 1943, now Patent No. 2,400,136, dated May 14, 1945, the strut legs 31 and the ring 50 cooperate so as to limit the rate of temperature increase of the spring ngers 42 that rate oi decrease of modulus of elasticity of the spring iingers will be commensurate with the rate of increase of the resistance of the magnet coil i8 due to the effect of passage of electric current therethrough. Therefore, during the warm-up period of the regulator, there will be practically no variation of regulated voltage; and, at the end of the warm-up period when equilibrium between the differential of spring temperature and magnet coil temperature is reached, the regulation will remain practically l,

the same as at the outset. In other words, the heating of the spring ngers l2 is so controlled as to compensate for the heating of the magnet coil.

f V{I'he present invention provides compensation section in Fig. 2. The unit 'i0 comprises two y,

dished washers 'H and l2 having flat annular surfaces adapted to engage the adjacent carbon discs such as 24a and 24D and having pockets 13 and 'I4 respectively for receiving the head 'l5 of -a rivet and a washer l over which the rivet is formed at 11. In order that there `may be relative movement between theV discs 'H and 12, the rivet 'l5 is not swedged so tightly as to take up all. the clearance. Fig. 2 shows that normally there is a small gap 'i8 between the parts 1l and 12 which are maintained in eX- tended relation by a bimetal Washer 'i9 comprising two dished rings, namely, ring 80 of metal having higher temperature coeiiicient of expansion and a disc 8l of metal having lower temperature coefficient of expansion. The unit l!! is preferably located near the right end of tube 23 where it will be likely to be the most responsive to temperature changes in the carbon pile. As the temperature increases, the thickness of the carbon discs 24 increases, thereby tending to increase the pressure between the discs and thus interfering with regulation. However, the

unit 10 operates to offset the tendency to increase the'all-ove'r length of the carbon pile since, as Vtemperature increases, the bimetal member 'i9 tends to bend toward a more attened position thereby permitting the gap 18 to be decreased so that the all-over length of the carbon pile including the unit 'l0 will remain the same regardless of temperature.

In order that the regulator will not otherwise bel affected by changes in temperature, the studs 20 and the strut 36 are made of metal having practically zero temperature coefficient of expansion such as Invar metal.

When the load on the generator is suddenly diminished, there is a tendency to increase its voltage suddenly, thereby causing a sudden increase of pull of the magnet of the regulator. If the armature were free to respond to the sudden pull of the magnet, its amplitude of oscillation would be abnormal and would tend to oscillate an unusual length of time before returning to equilibrium. Abnormal oscillation of the armature is resisted in the following manner. Normally disc 5l olers small resistance to movement of the armature, but increases in stiffness rapidly as the armature moves an abnormal distance toward the diaphragm thereby tending to reduce motion toward the magnet. The compression of the air between the discs 5l and 53 also reduces this motion. If the armature still moves too far toward the magnet, the generator eld current is over-reduced, generator voltage drops abnormally, and magnetic pull on the armature decreases suddenly with the result that springs 42 are permitted quickly to move the armature away from the magnet. ,As disc El rapidly approaches the ring 5S, air between these parts is rapidly compressed and motion of the armature away from the magnet is reduced. Thus, by preventing normal oscillation of the armature under these conditions, stability of operation is obtained. At the joint between the ring 52 and the discs, there is a restricted ow of air out of and into the space between the discs.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

l. In combination, a pair of parallel discs having a central recess portion extending inwardly from their outer plane surfaces;V an apertured dished bimetallic element disposed between the discs and engaging both of the discs and urging said discs in a direction away from each other, said binietallic member being operable to become more at when subjected to heat whereby the discs can move toward each other; and means loosely extending through the washers and the bimetallic member and having portions loosely overlapping the discs within the connes of their respective recess portions and in a manner to hold the discs and bimetallic member in assembled relation, said overlapping portions being so dimensioned to permit relative movement between the discs without the overlapping portions extending beyond the outer faces of both discs when same moves their full distance toward each other.

2. An electrically conducting spacer unit adapted to be used between a terminal and an eXpansible member comprising a Vplurality of washers, an apertured dished bimetallic' element located between two of the washers and in physical contact therewith and operating to change its shape when subjected to heat whereby the thickness of the spacer unit decreases to Colnpensate for any increaseV in thickness of anexpansible member; and means extending loosely through the washers and the element and having a portion at each end loosely overlying portions of end washers limiting axial separations of the washers and also retaining the washers and elements in assembled relation while permitting change in the spacing of the washers toward each other during the change of shape of the element.

3. A compensating unit of the character described the same comprising a member having spaced abutments thereon, said member having a pair of metallic washers mounted longitudinally slidable thereon with an apertured dished shaped bimetallic element interposed between and in physical contact with the washers and normally urging said washers in a direction away from each other and against the respective abutments, said element iiattening out when subject to heat to permit the washers to move toward each other.

4. An electrically conducting spacer unit comprising a pair of parallel discs, each disc having a depressed central portion on its outer face; an apertured dished bimetallic washer located between and contacting the discs and operating to urge the discs in a direction away from each other; a member extending through the washer; means carried by the member located within the confines of the depressed central portion of the discs to limit axial separation of the discs and also retaining the discs and washer in assembled relation while permitting change in the spacing of the discs toward each other during the change of shape of the bimetallic washer.

5. A compensating unit of the character described, the same comprising a metallic member having spaced stops thereon; a pair of similarly formed discs having depressed central portions on their outer faces for housing the stops and a projection on their inner faces with the projections facing each other, said discs being apertured and slidable longitudinally on the member, a dished bimetallic washer interposed between the discs and in physical contact with the discs and urging same in a direction away from each other and against the respective stops so as to provide an air gap between the projection, said bimetallic washer flattening out when subjected to heat to permit the discs to move longitudinally toward each other as the bimetallic member changes its shape.

W'ILLIAM J. RADY.

LYMAN A. RICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,894,842 Appelberg Jan. 17, 1933 2,045,289 Bolin June 23, 1936 2,395,007 Leupold Feb. 19, 1946 2,405,514 Neild Aug. 6, 1946 

